Re: [PATCH v3 1/2] mm: page_alloc: skip memoryless nodes entirely

Ingo Molnar
2023-10-20T08:31:18Z

* Qi Zheng <zhengqi.arch@bytedance.com> wrote:

> In find_next_best_node(), We skipped the memoryless nodes

s/We
/we

s/the memoryless nodes
/memoryless nodes

> when building the zonelists of other normal nodes (N_NORMAL),
> but did not skip the memoryless node itself when building
> the zonelist. This will cause it to be traversed at runtime.
>
> For example, say we have node0 and node1, node0 is memoryless
> node, then the fallback order of node0 and node1 as follows:
>
> [ 0.153005] Fallback order for Node 0: 0 1
> [ 0.153564] Fallback order for Node 1: 1
>
> After this patch, we skip memoryless node0 entirely, then
> the fallback order of node0 and node1 as follows:

s/fallback
/fall back

>
> [ 0.155236] Fallback order for Node 0: 1
> [ 0.155806] Fallback order for Node 1: 1
>
> So it becomes completely invisible, which will reduce runtime
> overhead.
>
> And in this way, we will not try to allocate pages from memoryless
> node0, then the panic mentioned in [1] will also be fixed. Even though
> this problem has been solved by dropping the NODE_MIN_SIZE constrain
> in x86 [2], it would be better to fix it in core MM as well.

s/in core MM
/in the core MM

> [1]. https://lore.kernel.org/all/20230212110305.93670-1-zhengqi.arch@bytedance.com/
> [2]. https://lore.kernel.org/all/20231017062215.171670-1-rppt@kernel.org/
>
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> Acked-by: David Hildenbrand <david@redhat.com>

> + /*
> + * Use the local node if we haven't already. But for memoryless local
> + * node, we should skip it and fallback to other nodes.

s/fallback
/fall back

s/already. But
/already, but

Acked-by: Ingo Molnar <mingo@kernel.org>

Thanks,

Ingo